How do I clean a flat-screen TV covered with fingerprints?

Q: How do I remove fingerprints, including old ones, from a flat-screen TV?

A: Back when the only screens in most homes were televisions that showed images projected from the back via cathode-ray tubes, cleaning fingerprints from the glass was easy. Manufacturers coated the back of the glass with tiny phosphor dots that glowed red, green or blue when struck by electron beams from the tube. But they didn’t coat the front of the glass, so you could rub away fingerprints with the help of any window cleaner that worked on glass. You could even use products with ammonia, such as the original Windex formula. And fingerprints weren’t such an issue then; touch screens were yet to come.

Cleaning screens became more complicated beginning in the early aughts, when sales of plasma televisions took off, only to be nudged aside in later years by LCDs, OLEDs and QLEDs. Plasma televisions, the first flat screens, have two glass panels separated by a narrow gap filled with millions of tiny cells filled with gas that reacts when current passes through and causes phosphors on the inside of the glass to light up and create images. Glare from other nearby light sources made images on the screen hard to see, so manufacturers began applying anti-glare coating to the outside face of the glass. Cleaning with ammonia and some other cleaners could strip the coating and leave the screen with visible wipe marks. Improper cleaning can also permanently damage newer types of television screens, as well as computer and gaming screens.

Phone screens are also vulnerable, but they need to stand up to being taken in and out of jeans pockets so they resist abrasion better. Because screen materials vary, it’s always smart to check the manufacturer’s recommendations for your specific product. Search online for terms such as “clean Mac computer screen” or “clean Sony TV screen.”

But in all cases some general guidelines apply:

• First, unplug or power down the device and let it cool before you clean.

• Use a soft, clean microfiber cloth - ideally the type you’d use for eyeglasses or a camera lens - not a paper towel or tissue, which could scratch.

• Gently wipe the screen to remove dust and other loose dirt, without pressing in hard or rubbing.

• Also dust off the outside edges of the screen and any cabinetry or ledge supporting it. Often that’s all you’ll need to do.

• If the screen still looks dirty, slightly dampen the cloth with distilled water. Or switch to a clean cloth if the first one picked up a lot of dust. Spray the water onto the cloth with a squirt bottle, if possible, because that keeps the cloth drier than if you dunk it in water and then wring it out. (Using tap water is probably okay, but it could contain minerals and chlorine.) Never spray any cleaning solution, even water, directly onto the screen. Gently wipe across the screen with the damp cloth, again avoiding excessive pressure or any kind of scrubbing motion.

• To clean stubborn spots, you can use a screen cleaner, such as the iO Screen Cleaner Spray, which as of late July lists for $15.99 on Amazon in a kit that includes 16 ounces of cleaner and a microfiber cloth. But Consumer Reports, which tests flat-screen TVs and other devices with screens and often needs to clean them before photographing them, suggests the packaged solutions can be a waste of money. “Some of these kits cost $15 to $20 for just a microfiber cloth and a small bottle of cleaning solution, which is probably mostly water,” the Consumer Reports website says. “Instead, buy the cloth at an office supply store or online and use distilled water or a solution of your own making.”

• For that, it recommends diluting a few drops of clear hand dishwashing detergent in water. The magazine picked up that advice from Panasonic. The company’s U.S. site now recommends using a screen cleaner, but Panasonic websites for some other countries still recommend the homemade solution. The British site is one of several that suggests 1 part mild detergent to 100 parts water, which works out to approximately ½ teaspoon of detergent to 1 cup of water. As when you are using just water, moisten the cloth by spraying the cleaner onto the cloth and avoid rubbing hard in any area, which can damage screens.

• Avoid using compressed air, solvents such as benzene or acetone, cleaners that contain ammonia, chlorine bleach or an oxygen bleach, such as hydrogen peroxide.

• When it’s necessary to sanitize screens, some manufacturers recommend using isopropyl alcohol diluted in water. (Dell suggests 70 percent alcohol to 30 percent water.) But be cautious, because repeated use of alcohol, even diluted, can damage screens. In a home, you may never need to sanitize screens.

• But you might want to sanitize a remote control to prevent spreading colds or other illnesses. For that, Consumer Reports recommends wearing disposable or rubber gloves, opening a window, removing the batteries, tipping the remote upside down to loosen debris, and then wiping down the surfaces. Use a cloth dampened in a mixture of 70 percent isopropyl alcohol and 30 percent water, or another sanitizer recommended by the federal Centers for Disease Control and Prevention. After you sanitize, wipe off the remote with a cloth dampened with clear water and then dry it with another cloth.